US1376805A - Process of producing a surrogate for tannin - Google Patents

Description

' UNITED stares.

rarest orriee.

CARL GRAF, OF COLOGNE-RODENKIRCHEN, GERMANY, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO THE CHEMICAL FOUNDATION, INC., A CORPORATION OF DELAWARE.

PROCESS OF PRODUCING A SUBROGATE FOR TANNIN'.

No Drawing.

To all whom it may concern:

Be it known that I, CARL GnAr, a subject of the King of Wurttemberg, residing at Cologne-Rodenkirchen, Germany, have invented certain new and useful Improvements in Processes of Producing a Surrogate for Tannin, of which the following is a specification.

The present invention relates to a process of producing a surrogate for tannin, adapted to be employed both alone for itself and also mixed with the extracts of the vegetable tanning materials hitherto employed for the manufacture of leather ready for use, without thereby altering in the least the ordinary manner of working.

The starting material of the process is tar, be it common coal-tar or brown coal-tar, or different kinds of tar extracted from peat or wood. The important elements for the present process are separated from the tar by a preliminary treatment with water or with alkalis, neutral or basic salts or other equivalents. The preliminary treatment with these materials has, compared to that with water, the advantage, that the chief material is better utilized thanby treatment only with water. From the tar a liquid will be separated to which sulfates of aluminium and copper are added. In lieu of the sulfate of aluminium we may also use for ex ample, however, the other equivalents such as potassium alum, chrome alum and ammonium alum. The liquid obtained in this way is employed for tanning leather. As a residue-a tough, pitch-like mass remains, from which by a repeated treatment with the above-named materials surrogates for tannin may be prepared.

It is possible, to introduce in the preliminary treatment the materials to be added in the aftertreatment, such. as the sulfates of aluminium and copper. We thereby obtain a product that may, in case of need, also be made use of for tanning leather. The result obtained is, however, less favorable by far than if the materials in question are added only in the after-treatment. more, possible to attain a tanning action by the employment of only one of the sulfates referred to. But, if only sulfate of copper be used, the tanning action is considerably weaker and the leather is less filled, than will be the case if sulfate of aluminium or any of the sulfates or alums, applicable in its Specification of Letters Patent.

Application filed March 11, 1916.

It is, further.

Patented May 3, 1921. Serial No. 83,613.

place be added. On the contrary, by the addition of sulfates ofaluminium and the like the liquid is improved to such a degree,

that it presents qualities similar to those of,

extracts of vegetable substances. If, on the contrary, the sulfate of copper be omitted, theleather acquires a dark-gray color, which 1s, in most cases, not wished for.

The process may be carried out both in the cold and at an increased temperature, it

being, however, hastened if the temperature rises. Y

As an example, in 100 lbs. of water 20 to 25 lbs. of sulfite of soda or equivalent material will be dissolved. To this solution 50 lbs. of tar, e. g. beech-wood tar are added,

when the whole mixture is agitated for some time. Now Sto 10 lbs. of sulfate of aluminium or 6 to 7 lbs. of alum are added un der contlnuous stirring; the stirring operation is then stopped and l to 2 lbs. of sulfate of copper are added, whereupon the stirrer is continued. The liquid obtained by this treatment may at once be employed for tanning or may be inspissated by evaporation. I

What I claim is:

1. That process of producing a surrogate for tannin, which comprises treating about 50 lbs. of tar with a solution comprising 100 lbs. of water and 20 to 25 lbs. of sulfite of soda or its equivalent; adding and thoroughly mixing with this mixture 8 to 10 lbs. of sulfate of aluminum or its equivalent;

adding to the mixture thus obtained 1 to 2 lbs. of sulfate of copper.

2. That process of producing a surrogate for tannin, which comprises treating tar with an aqueous solution of an alkali or its equivalent; and thoroughly mixing with the liquid thus obtained a metallic sulfate or mixture'of metallic sulfates.

3. That process of producing a surrogate for tannin, which comprises treating tar with an aqueous solution of an alkali or its equivalent; separating the liquid thus obtained; and treating said liquid with sulfate of copper and sulfate of aluminum.

In testimony whereof I affix my signature in presence of two witnesses.

CARL GRAF.

Witnesses:

, T. F. LoUN'rs,

H. HENDEL.